chrono::ChMatterSPH Class Reference

Description

Class for clusters of point nodes that can simulate a fluid or an elastic/plastic solid with the Smooth Particle Hydrodynamics (SPH) approach, that is with a 'meshless' FEA approach.

#include <ChMatterSPH.h>

Inheritance diagram for chrono::ChMatterSPH:
Collaboration diagram for chrono::ChMatterSPH:

Public Member Functions

 ChMatterSPH ()
 Build a cluster of nodes for SPH and meshless FEM. More...
 
 ChMatterSPH (const ChMatterSPH &other)
 
virtual ChMatterSPHClone () const override
 "Virtual" copy constructor (covariant return type).
 
void SetCollide (bool mcoll)
 Enable/disable the collision for this cluster of particles. More...
 
virtual bool GetCollide () const override
 Tell if the object is subject to collision. More...
 
virtual int GetDOF () override
 Get the number of scalar coordinates (variables), if any, in this item.
 
virtual unsigned int GetNnodes () const override
 Get the number of nodes.
 
virtual std::shared_ptr
< ChNodeBase
GetNode (unsigned int n) override
 Access the N-th node.
 
void ResizeNnodes (int newsize)
 Resize the node cluster. More...
 
void AddNode (ChVector< double > initial_state)
 Add a new node to the particle cluster, passing a vector as initial position. More...
 
void SetMaterialSurface (const std::shared_ptr< ChMaterialSurfaceBase > &mnewsurf)
 Set the material surface for 'boundary contact'.
 
virtual std::shared_ptr
< ChMaterialSurfaceBase > & 
GetMaterialSurfaceBase ()
 Set the material surface for 'boundary contact'.
 
virtual void IntStateGather (const unsigned int off_x, ChState &x, const unsigned int off_v, ChStateDelta &v, double &T) override
 From item's state to global state vectors y={x,v} pasting the states at the specified offsets. More...
 
virtual void IntStateScatter (const unsigned int off_x, const ChState &x, const unsigned int off_v, const ChStateDelta &v, const double T) override
 From global state vectors y={x,v} to item's state (and update) fetching the states at the specified offsets. More...
 
virtual void IntStateGatherAcceleration (const unsigned int off_a, ChStateDelta &a) override
 From item's state acceleration to global acceleration vector.
 
virtual void IntStateScatterAcceleration (const unsigned int off_a, const ChStateDelta &a) override
 From global acceleration vector to item's state acceleration.
 
virtual void IntLoadResidual_F (const unsigned int off, ChVectorDynamic<> &R, const double c) override
 Takes the F force term, scale and adds to R at given offset: R += c*F.
 
virtual void IntLoadResidual_Mv (const unsigned int off, ChVectorDynamic<> &R, const ChVectorDynamic<> &w, const double c) override
 Takes the M*v term, multiplying mass by a vector, scale and adds to R at given offset: R += c*M*w.
 
virtual void IntToDescriptor (const unsigned int off_v, const ChStateDelta &v, const ChVectorDynamic<> &R, const unsigned int off_L, const ChVectorDynamic<> &L, const ChVectorDynamic<> &Qc) override
 Prepare variables and constraints for a solution: From a vector R into the F 'force' term of the variables From a vector Qc into the Qb 'constraint' term of the constraints From a vector v into the q 'unknowns' term of the variables (for warm starting) From a vector L into the L 'lagrangian ' term of the constraints (for warm starting)
 
virtual void IntFromDescriptor (const unsigned int off_v, ChStateDelta &v, const unsigned int off_L, ChVectorDynamic<> &L) override
 After a solver solution, fetch values from variables and constraints: To a vector v from the q 'unknowns' term of the variables To a vector L from the L 'lagrangian ' term of the constraints.
 
virtual void VariablesFbReset () override
 Sets the 'fb' part of the encapsulated ChVariablesBody to zero.
 
virtual void VariablesFbLoadForces (double factor=1) override
 Adds the current forces applied to body (including gyroscopic torque) in encapsulated ChVariablesBody, in the 'fb' part: qf+=forces*factor.
 
virtual void VariablesQbLoadSpeed () override
 Initialize the 'qb' part of the ChVariablesBody with the current value of body speeds. More...
 
virtual void VariablesFbIncrementMq () override
 Adds M*q (masses multiplied current 'qb') to Fb, ex. More...
 
virtual void VariablesQbSetSpeed (double step=0) override
 Fetches the body speed (both linear and angular) from the 'qb' part of the ChVariablesBody (does not updates the full body&markers state) and sets it as the current body speed. More...
 
virtual void VariablesQbIncrementPosition (double step) override
 Increment body position by the 'qb' part of the ChVariablesBody, multiplied by a 'step' factor. More...
 
virtual void InjectVariables (ChSystemDescriptor &mdescriptor) override
 Tell to a system descriptor that there are variables of type ChVariables in this object (for further passing it to a solver) Basically does nothing, but maybe that inherited classes may specialize this. More...
 
void SetNoSpeedNoAcceleration () override
 Set no speed and no accelerations (but does not change the position)
 
virtual void SyncCollisionModels () override
 Synchronize coll.models coordinates and bounding boxes to the positions of the particles.
 
virtual void AddCollisionModelsToSystem () override
 If this physical item contains one or more collision models, add them to the system's collision engine. More...
 
virtual void RemoveCollisionModelsFromSystem () override
 If this physical item contains one or more collision models, remove them from the system's collision engine. More...
 
void UpdateParticleCollisionModels ()
 
ChContinuumSPHGetMaterial ()
 Access the material.
 
void FillBox (const ChVector<> size, const double spacing, const double initial_density, const ChCoordsys<> cords=CSYSNORM, const bool do_centeredcube=true, const double kernel_sfactor=2.2, const double randomness=0.0)
 Initialize the fluid as a prismatic region filled with nodes, initially well ordered as a lattice. More...
 
virtual void Update (double mytime, bool update_assets=true) override
 Update all auxiliary data of the particles.
 
virtual void Update (bool update_assets=true) override
 Update all auxiliary data of the particles.
 
virtual void ArchiveOUT (ChArchiveOut &marchive) override
 Add a new node to the particle cluster, passing a vector as initial position. More...
 
virtual void ArchiveIN (ChArchiveIn &marchive) override
 Method to allow de serialization of transient data from archives.
 
- Public Member Functions inherited from chrono::ChIndexedNodes
 ChIndexedNodes (const ChIndexedNodes &other)
 
- Public Member Functions inherited from chrono::ChPhysicsItem
 ChPhysicsItem (const ChPhysicsItem &other)
 
ChSystemGetSystem () const
 Get the pointer to the parent ChSystem()
 
virtual void SetSystem (ChSystem *m_system)
 Set the pointer to the parent ChSystem() and also add to new collision system / remove from old coll.system.
 
void AddAsset (std::shared_ptr< ChAsset > masset)
 Add an optional asset (it can be used to define visualization shapes, es ChSphereShape, or textures, or custom attached properties that the user can define by creating his class inherited from ChAsset)
 
std::vector< std::shared_ptr
< ChAsset > > & 
GetAssets ()
 Access to the list of optional assets.
 
std::shared_ptr< ChAssetGetAssetN (unsigned int num)
 Access the Nth asset in the list of optional assets.
 
virtual ChFrame GetAssetsFrame (unsigned int nclone=0)
 Get the master coordinate system for assets that have some geometric meaning. More...
 
virtual unsigned int GetAssetsFrameNclones ()
 Optionally, a ChPhysicsItem can return multiple asset coordinate systems; this can be helpful if, for example, when a ChPhysicsItem contains 'clones' with the same assets (ex. More...
 
virtual void GetTotalAABB (ChVector<> &bbmin, ChVector<> &bbmax)
 Get the entire AABB axis-aligned bounding box of the object. More...
 
virtual void GetCenter (ChVector<> &mcenter)
 Get a symbolic 'center' of the object. More...
 
virtual void StreamINstate (ChStreamInBinary &mstream)
 Method to deserialize only the state (position, speed) Must be implemented by child classes. More...
 
virtual void StreamOUTstate (ChStreamOutBinary &mstream)
 Method to serialize only the state (position, speed) Must be implemented by child classes. More...
 
virtual void Setup ()
 This might recompute the number of coordinates, DOFs, constraints, in case this might change (ex in ChAssembly), as well as state offsets of contained items (ex in ChMesh)
 
virtual int GetDOF_w ()
 Get the number of scalar coordinates of variables derivatives (usually = DOF, but might be different than DOF, ex. More...
 
virtual int GetDOC ()
 Get the number of scalar constraints, if any, in this item.
 
virtual int GetDOC_c ()
 Get the number of scalar constraints, if any, in this item (only bilateral constr.) Children classes might override this. More...
 
virtual int GetDOC_d ()
 Get the number of scalar constraints, if any, in this item (only unilateral constr.) Children classes might override this. More...
 
unsigned int GetOffset_x ()
 Get offset in the state vector (position part)
 
unsigned int GetOffset_w ()
 Get offset in the state vector (speed part)
 
unsigned int GetOffset_L ()
 Get offset in the lagrangian multipliers.
 
void SetOffset_x (const unsigned int moff)
 Set offset in the state vector (position part) Note: only the ChSystem::Setup function should use this.
 
void SetOffset_w (const unsigned int moff)
 Set offset in the state vector (speed part) Note: only the ChSystem::Setup function should use this.
 
void SetOffset_L (const unsigned int moff)
 Set offset in the lagrangian multipliers Note: only the ChSystem::Setup function should use this.
 
virtual void IntStateGatherReactions (const unsigned int off_L, ChVectorDynamic<> &L)
 From item's reaction forces to global reaction vector. More...
 
virtual void IntStateScatterReactions (const unsigned int off_L, const ChVectorDynamic<> &L)
 From global reaction vector to item's reaction forces. More...
 
virtual void IntStateIncrement (const unsigned int off_x, ChState &x_new, const ChState &x, const unsigned int off_v, const ChStateDelta &Dv)
 Computes x_new = x + Dt , using vectors at specified offsets. More...
 
virtual void IntLoadResidual_CqL (const unsigned int off_L, ChVectorDynamic<> &R, const ChVectorDynamic<> &L, const double c)
 Takes the term Cq'*L, scale and adds to R at given offset: R += c*Cq'*L. More...
 
virtual void IntLoadConstraint_C (const unsigned int off, ChVectorDynamic<> &Qc, const double c, bool do_clamp, double recovery_clamp)
 Takes the term C, scale and adds to Qc at given offset: Qc += c*C. More...
 
virtual void IntLoadConstraint_Ct (const unsigned int off, ChVectorDynamic<> &Qc, const double c)
 Takes the term Ct, scale and adds to Qc at given offset: Qc += c*Ct. More...
 
virtual void InjectConstraints (ChSystemDescriptor &mdescriptor)
 Tell to a system descriptor that there are contraints of type ChConstraint in this object (for further passing it to a solver) Basically does nothing, but maybe that inherited classes may specialize this. More...
 
virtual void ConstraintsBiReset ()
 Sets to zero the known term (b_i) of encapsulated ChConstraints.
 
virtual void ConstraintsBiLoad_C (double factor=1, double recovery_clamp=0.1, bool do_clamp=false)
 Adds the current C (constraint violation) to the known term (b_i) of encapsulated ChConstraints.
 
virtual void ConstraintsBiLoad_Ct (double factor=1)
 Adds the current Ct (partial t-derivative, as in C_dt=0-> [Cq]*q_dt=-Ct) to the known term (b_i) of encapsulated ChConstraints.
 
virtual void ConstraintsBiLoad_Qc (double factor=1)
 Adds the current Qc (the vector of C_dtdt=0 -> [Cq]*q_dtdt=Qc ) to the known term (b_i) of encapsulated ChConstraints.
 
virtual void ConstraintsFbLoadForces (double factor=1)
 Adds the current link-forces, if any, (caused by springs, etc.) to the 'fb' vectors of the ChVariables referenced by encapsulated ChConstraints.
 
virtual void ConstraintsLoadJacobians ()
 Adds the current jacobians in encapsulated ChConstraints.
 
virtual void ConstraintsFetch_react (double factor=1)
 Fetches the reactions from the lagrangian multiplier (l_i) of encapsulated ChConstraints. More...
 
virtual void InjectKRMmatrices (ChSystemDescriptor &mdescriptor)
 Tell to a system descriptor that there are items of type ChKblock in this object (for further passing it to a solver) Basically does nothing, but maybe that inherited classes may specialize this. More...
 
virtual void KRMmatricesLoad (double Kfactor, double Rfactor, double Mfactor)
 Adds the current stiffness K and damping R and mass M matrices in encapsulated ChKblock item(s), if any. More...
 
- Public Member Functions inherited from chrono::ChObj
 ChObj (const ChObj &other)
 
int GetIdentifier () const
 Gets the numerical identifier of the object.
 
void SetIdentifier (int id)
 Sets the numerical identifier of the object.
 
double GetChTime () const
 Gets the simulation time of this object.
 
void SetChTime (double m_time)
 Sets the simulation time of this object.
 
const char * GetName () const
 Gets the name of the object as C Ascii null-terminated string -for reading only!
 
void SetName (const char myname[])
 Sets the name of this object, as ascii string.
 
std::string GetNameString () const
 Gets the name of the object as C Ascii null-terminated string.
 
void SetNameString (const std::string &myname)
 Sets the name of this object, as std::string.
 
void MFlagsSetAllOFF (int &mflag)
 
void MFlagsSetAllON (int &mflag)
 
void MFlagSetON (int &mflag, int mask)
 
void MFlagSetOFF (int &mflag, int mask)
 
int MFlagGet (int &mflag, int mask)
 

Additional Inherited Members

- Protected Attributes inherited from chrono::ChPhysicsItem
ChSystemsystem
 parent system
 
std::vector< std::shared_ptr
< ChAsset > > 
assets
 set of assets
 
unsigned int offset_x
 offset in vector of state (position part)
 
unsigned int offset_w
 offset in vector of state (speed part)
 
unsigned int offset_L
 offset in vector of lagrangian multipliers
 
- Protected Attributes inherited from chrono::ChObj
double ChTime
 the time of simulation for the object
 

Constructor & Destructor Documentation

chrono::ChMatterSPH::ChMatterSPH ( )

Build a cluster of nodes for SPH and meshless FEM.

By default the cluster will contain 0 particles.

Member Function Documentation

void chrono::ChMatterSPH::AddCollisionModelsToSystem ( )
overridevirtual

If this physical item contains one or more collision models, add them to the system's collision engine.

Reimplemented from chrono::ChPhysicsItem.

void chrono::ChMatterSPH::AddNode ( ChVector< double >  initial_state)

Add a new node to the particle cluster, passing a vector as initial position.

void chrono::ChMatterSPH::ArchiveOUT ( ChArchiveOut marchive)
overridevirtual

Add a new node to the particle cluster, passing a vector as initial position.

Resize the node cluster. Also clear the state of previously created particles, if any. Number of coordinates of the node cluster Method to allow serialization of transient data to archives.

Reimplemented from chrono::ChIndexedNodes.

void chrono::ChMatterSPH::FillBox ( const ChVector<>  size,
const double  spacing,
const double  initial_density,
const ChCoordsys<>  cords = CSYSNORM,
const bool  do_centeredcube = true,
const double  kernel_sfactor = 2.2,
const double  randomness = 0.0 
)

Initialize the fluid as a prismatic region filled with nodes, initially well ordered as a lattice.

This is a helper function so that you avoid to create all nodes one by one with many calls to AddNode() .

Parameters
sizex,y,z sizes of the box to fill (better if integer multiples of spacing)
spacingthe spacing between two near nodes
initial_densitydensity of the material inside the box, for initialization of node's masses
cordsposition and rotation of the box
do_centeredcubeif false, array is simply cubic, if true is centered cubes (highest regularity)
kernel_sfactorthe radius of kernel of the particle is 'spacing' multiplied this value
randomnessrandomness of the initial distribution lattice, 0...1
virtual bool chrono::ChMatterSPH::GetCollide ( ) const
overridevirtual

Tell if the object is subject to collision.

Only for interface; child classes may override this, using internal flags.

Reimplemented from chrono::ChPhysicsItem.

void chrono::ChMatterSPH::InjectVariables ( ChSystemDescriptor mdescriptor)
overridevirtual

Tell to a system descriptor that there are variables of type ChVariables in this object (for further passing it to a solver) Basically does nothing, but maybe that inherited classes may specialize this.

Reimplemented from chrono::ChPhysicsItem.

void chrono::ChMatterSPH::IntStateGather ( const unsigned int  off_x,
ChState x,
const unsigned int  off_v,
ChStateDelta v,
double &  T 
)
overridevirtual

From item's state to global state vectors y={x,v} pasting the states at the specified offsets.

Reimplemented from chrono::ChPhysicsItem.

void chrono::ChMatterSPH::IntStateScatter ( const unsigned int  off_x,
const ChState x,
const unsigned int  off_v,
const ChStateDelta v,
const double  T 
)
overridevirtual

From global state vectors y={x,v} to item's state (and update) fetching the states at the specified offsets.

Reimplemented from chrono::ChPhysicsItem.

void chrono::ChMatterSPH::RemoveCollisionModelsFromSystem ( )
overridevirtual

If this physical item contains one or more collision models, remove them from the system's collision engine.

Reimplemented from chrono::ChPhysicsItem.

void chrono::ChMatterSPH::ResizeNnodes ( int  newsize)

Resize the node cluster.

Also clear the state of previously created particles, if any.

void chrono::ChMatterSPH::SetCollide ( bool  mcoll)

Enable/disable the collision for this cluster of particles.

After setting ON, remember RecomputeCollisionModel() before anim starts (it is not automatically recomputed here because of performance issues.)

void chrono::ChMatterSPH::VariablesFbIncrementMq ( )
overridevirtual

Adds M*q (masses multiplied current 'qb') to Fb, ex.

if qb is initialized with v_old using VariablesQbLoadSpeed, this method can be used in timestepping schemes that do: M*v_new = M*v_old + forces*dt

Reimplemented from chrono::ChPhysicsItem.

void chrono::ChMatterSPH::VariablesQbIncrementPosition ( double  step)
overridevirtual

Increment body position by the 'qb' part of the ChVariablesBody, multiplied by a 'step' factor.

pos+=qb*step

If qb is a speed, this behaves like a single step of 1-st order numerical integration (Eulero integration). Does not automatically update markers & forces.

Reimplemented from chrono::ChPhysicsItem.

void chrono::ChMatterSPH::VariablesQbLoadSpeed ( )
overridevirtual

Initialize the 'qb' part of the ChVariablesBody with the current value of body speeds.

Note: since 'qb' is the unknown, this function seems unuseful, unless used before VariablesFbIncrementMq()

Reimplemented from chrono::ChPhysicsItem.

void chrono::ChMatterSPH::VariablesQbSetSpeed ( double  step = 0)
overridevirtual

Fetches the body speed (both linear and angular) from the 'qb' part of the ChVariablesBody (does not updates the full body&markers state) and sets it as the current body speed.

If 'step' is not 0, also computes the approximate acceleration of the body using backward differences, that is accel=(new_speed-old_speed)/step. Mostly used after the solver provided the solution in ChVariablesBody .

Reimplemented from chrono::ChPhysicsItem.